Backside reflection optical display
The disclosure generally involves an optical (perhaps flat panel) display utilizing backside reflection for time-multiplexed optical shuttering. One display comprises a side-illuminated light guide associated with conditions for total internal reflection. A first surface of the light guide is elastomeric. Disposed against this elastomeric surface is an active layer that selectively deforms the elastomeric surface in locations that can correspond to display pixels. This resulting change in the geometry of the elastomeric surface can be sufficient to defeat the conditions for total internal reflection. When appropriate, light is reflected by the particular deformation and is ejected from another surface of the light guide. In this case, each location that allows light to exit could represent an activated display pixel. In certain situations, color flat panel displays of varying sizes may further implement field sequential color and time-multiplexed optical shuttering.
The present disclosure generally relates to the field of display devices and, more particularly, to an optical (perhaps flat panel) display utilizing backside reflection.
BACKGROUNDCertain flat panel displays exploit the principle of frustrated total internal reflection (FTIR) to induce the emission of light from the respective system. Such displays may be achieved through the utilization of microelectromechanical systems or nanoelectromechanical systems (often collectively referred to as MEMS). For example, one representative of FTIR-based MEMS devices may be a time multiplexed optical shuttering (TMOS) display. These TMOS devices may each be generally able to selectively frustrate the light undergoing total internal reflection within a (generally) planar waveguide. When such frustration occurs, the selected region of frustration may constitute a pixel capable of external control.
SUMMARYAt a high level, this disclosure describes optical displays incorporating or otherwise using backside reflection. More specifically, in certain embodiments, a flat panel or other TMOS display may present pixels that are activated by violating the conditions for total internal reflection within a light guide or its light guidance substrate. For example, an optical component may include a light guide adapted to conduct light wherein at least some portion of the light guide is deformable and an active layer disposed on the light guide whereby the active layer selectively reflects light by deforming a first surface of the light guide such that light is ejected from a second surface of the light guide. In certain situations, the deformable portion of the light guide may be a deformable elastomer layer. The deformable elastomer layer can then be disposed between the first surface of a light guidance substrate of the light guide and the active layer.
In another example, an optical display comprises a light guide adapted to conduct light under conditions of total internal reflection, with at least a portion of the light guide being deformable. An active layer is disposed on the light guide whereby the active layer selectively reflects light by selectively deforming a first surface of the light guide such that light is ejected from a second surface of the light guide. The display also includes a light source—potentially capable of outputting alternating pulses of primary colored or infrared light—coupled with the light guide.
In a further example, an optical display comprises a light guide adapted to conduct light under conditions of total internal reflection where at least a portion of the light guide is deformable. A plurality of modular active layer disposed in an arrayed manner on a deformable surface of the light guide whereby the modular active layer reflects light by selectively deforming a first surface of the light guide such that light is ejected from a second surface of the light guide. This display also includes a light source—potentially capable of outputting alternating pulses of primary colored or infrared light—coupled with the light guide.
To control these example displays or components thereof, instructions may be executed as appropriate. The instructions may cause a light source to output alternating pulses of light through a light guide adapted to conduct light under conditions of total internal reflection, with at least a portion of the light guide being deformable. The instructions may (often concurrently) selectively apply an electrostatic field to an active layer disposed on a first side of the light guide to deform a particular portion of the first surface of the light guide such that the light is ejected from a second surface of the light guide.
A method for fabricating such optical displays may include selecting a light guide adapted to conduct light under conditions of total internal reflection, with at least a portion of the light guide being deformable. The method may further include coupling a light source, capable of outputting alternating pulses of light, to the light guide and arranging a plurality of modules on the light guide. Each module could comprise an active layer and a driving layer, with the active layer disposed on a first surface of the light guide such that light is ejected from a second surface of the light guide upon selective deformation of the active layer by the driving layer.
The foregoing methods—as well as other disclosed example methods—may be computer managed or implementable. For example, the display may include processors or other control architecture that implements some or all of the example techniques. Put another way, some or all of these features or aspects may be further included or implemented in respective software. Generally, such features or aspects of these and other embodiments are set forth in the accompanying drawings and the description below. For example, some of these embodiments may be able to locally violate the conditions of total internal reflection on the surface of the waveguide that is opposite (and typically parallel) to the surface from which light is ejected. In this case, the optical path between the viewer and the light ejected from the display can be less obstructed, thereby resulting in a brighter, more efficient display. Indeed, a MEMS-based or other active layer may not be made of optically transparent materials since it will not lie within the optical path of the viewer. Therefore, a wider range of materials may be considered, which can result in cost reduction. Also, this may allow flat panel displays to be constructed of smaller modular components of fixed cost that have a more linear cost curve. This cost savings could make very large displays (e.g. optical display billboards) more affordable and easier to realize.
Another advantage potentially provided by such backside reflection could include a more parallel manufacturing or fabrication process. For example, the described displays could be manufactured with more independent, interchangeable parts that benefit from a parallel manufacturing process. In other words, the interchangeable parts may be fabricated independently and assembled into a final product, thereby possibly reducing production costs as well as the overall time of production. Further, interchangeable parts can facilitate repair.
Of course, these example features are for illustration purposes only and some or all may not be fully present (if at all) in certain embodiments. Other features, objects, and advantages will be apparent from the description and drawings and from the example claims.
At a high level,
Generally, the present disclosure discusses an optical display 100 that emits light by disposing guidance deforming components (such as an active layer 300) on one surface of an optical waveguide (or light guide) such that light is reflected or otherwise ejected from another surface. The deformation of the light guide frustrates total internal reflection causing light to be ejected locally at the surface opposing some portion of each deformation. More specifically, by selectively deforming one surface of a light guidance substrate such that the conditions for total internal reflection within the light guidance substrate are locally violated, light within the light guidance substrate is reflected at these deformations at an angle sufficient to exit the light guide at another surface of the light guide.
As shown in
An aggregate MEMS-based structure may form an active layer 300 (shown in
Disposed along at least one edge of the light guide 200 is a light source 110 capable of emitting pulses of light. This light source 110 may be operable to emit visible light, infrared, or any other suitable light wave. For example, an infrared lamp may be disposed next to colored lamps. The sources are chosen to emit the primary colors of visible light to achieve the desired color gamut of the display. Typically the sources are red, green and blue light emitting diodes that can be temporally multiplexed to provide the familiar color gamut known to color displays. In this example, short bursts of red, green and blue light are emitted through the same dot so quickly that the eye also sees them as a single color. In this case, different durations of red, green and blue create different shades and hues. More specifically, the duration of the charge helps control the opening and closing of the particular pixel. It is this duration that can determine the relative intensity of the color. One frequency for a full cycle of such alternations (red-green-blue) is typically 1/60 second. Thus every second, red, green and blue are flashed into the guidance substrate 60 times each, meaning roughly 180 flashes total of all colors combined in a second. For example, to produce a white background, each appropriate pixel is open for the entire duration of the red, green and blue cycles. To produce black text on the white background, each pixel representing a letter (or portion thereof) is closed for the entire duration of each cycle. In another example, to produce fifty percent gray, each respective pixel is open for 50 percent of each red, green and blue cycle. In yet another example, to produce a blue background, each appropriate pixel is closed during red and green cycles, but open during the blue cycle. The shade of blue is determined by the percentage of the blue cycle that the pixel is open (perhaps 10%=deep blue and 100%=bright blue). In short, each pixel can be left open for different percentages of the red, green and blue cycles to produce millions of different colors and shades of gray, a technique commonly referred to as pulse width modulation (PWM). But it will be understood that optical display 100 may be used for any suitable purpose and any light and/or color may be used. For example, an infrared light source 110 can be utilized if such an application is appropriate. In this example, a color display 100 could be converted to an infrared display 100 by shutting down the red-green-blue cycle (or removing the RGB source) and coupling a continuous infrared source to the light guide.
For a color display using time multiplexed optical shuttering (TMOS), the light source 110 comprises a plurality of sources capable of outputting alternating pulses of monochromatic light, such as light emitting diodes (LEDs). To increase distribution and mixture of tristimulus light within the light guide 200, a linearly arrayed concatenation of LEDs may be used. The individual LEDs may be simplex or triplex structures based, at least in part, on an application's dimensional and power dissipation considerations. A simplex LED is a discrete element that emits only one primary color. A triplex LED combines all three tristimulus primaries within a more unitary package (where the respective junctions may even share a common reflector and potting compound). The mounting for these linear arrays may also serve as the primary heat sink for these power-intensive illuminating systems.
Often, the geometry of the encapsulating structure in which the junction is embedded helps determine the optimal separation between the light guide 200 insertion face and the light source 110. The consequence of this physical separation is the trigonometric restriction on the angles of incidence of light encountering the insertion face. Moreover, Fresnel insertion losses apply to light entering light guide 200 from the surrounding air: maximum insertion occurs when the rays enter normal to the insertion face, while insertion becomes increasingly attenuated for rays at glancing angles. Typically, these issues do not arise for architectures that actually embed the light source 110 within light guide 200 or otherwise avoid ray transit through air prior to light travel within light guide 200. For example, the LEDs may be directly coupled to the light guide 200 by means of a silicone bridge, thereby improving the range of useful angles injected into light guide 200. The coupling of light at the interface of the actuated active layer 300 and light guide 200 may be based on geometric considerations involving the nature of the two surfaces making contact. For example, Parylene (which may be prepared by deposition on silicon wafers) may yield good optical coupling due to reduced surface roughness and better contact intimacy. In another example, materials that are not flat (such as latex) can still couple well under even slight pressure, since the compliance of the elastic material causes the latex to conform to the surface of the light guide 200, thereby providing intimacy of contact without benefit of an initially high surface flatness specification. In fact, a hybridized structure where latex coating is added onto a membrane may be used. In some cases, intimacy of contact over a sufficiently large (>3λ) area may provide a sufficient coupling.
The selective deformation of a first surface of the light guide 200 results in light being locally ejected from a second surface of the light guide 200. Every component required to activate the pixel, in relation to the viewer, lies behind the surface from which light is reflected out of the light guide 200. Except for any protective coatings used in commercial applications, the optical path between the viewer and the point at which light is ejected from the light guide 200 is relatively unobstructed. More specifically, there may be no transparent conductors, thin film transistors, cladding layers, and such to cause loss. Furthermore, there is no need for the materials in the active layer 300 or driving layer 400 to be optically transparent. In fact, the common conductor 312 is often dark in color and non-reflective. This enables the substrate 420 to be made of an opaque material such as a wafer or printed circuit board. The drive circuit 422 can be disposed on the back of the substrate 420 using common, low-cost circuit board manufacturing techniques.
Pixel conductors 311 are patterned on the bottom surface of the flexible membrane 310. An opaque common conductor 312 is disposed on the top surface of the flexible membrane 310. The common conductor 312 is typically non-reflective so that light is not coupled into the active layer 300 when it comes into contact with the light guide 200. The surface of the common conductor 312 is preferably black in color to improve the contrast ratio of the emitted light, since that is what the viewer sees when the pixel is off. The surface of the common conductor 312 may be coated with a layer of small asperities 314, such as glass beads. A through-hole conductor 313 extends from common conductor 312 on the top of the flexible membrane 310 to the bottom surface for the purpose of providing a contact point for the common conductor and the driving layer 400 shown in
Returning to the illustrated embodiment, driving layer 400 may include a drive circuit 422 that can be placed on the bottom side of the substrate 420. In the illustrated example, a plurality of pad electrodes 421 is disposed on the top surface of the substrate 420. Each pad electrode 421 is disposed on the substrate 420 such that each pad electrode 421 can correspond to a pixel conductor 311 on the active layer 300. When the active layer 300 is brought into contact with the driving layer 400, each pad electrode 421 comes into contact with its corresponding pixel conductor 311 making an electrical connection. The through-hole conductor 313 will come into contact with a pad electrode 421 that drives the common conductor 312. The thickness of the pad electrodes 421 and any adhesive are typically sufficient to provide a standoff between the driving layer 400 and the active layer 300.
More particularly,
The pixel is activated by means of a pixel electrode 851 and the excitation of ACF 850 that lies directly above it. The dimensions of pixel electrode 851 are often matched to the size of a display pixel. Pixel conductors 311 may not be necessary since their electrical function has been replaced by the layer of ACF 850.
It will be understood that many of the preceding figures are not drawn to scale in an effort to aid the reader. Further, the preceding description discusses example techniques. But this disclosure contemplates using any suitable technique for performing these and other similar tasks. Accordingly, many of the steps may take place simultaneously and/or in different orders than as shown. Moreover, manufacturers or other parties may use methods with additional steps, fewer steps, and/or different steps, so long as the methods remain appropriate. While various embodiments have been described, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, while the terms “bottom” and “top” have been used to more easily describe the display, the display may be oriented in any suitable direction. Indeed, a particular deformable surface of the light guide may not be directly opposite (or parallel to) the surface emitting the light as appropriate. Accordingly, other embodiments are within the scope of the following claims.
Claims
1. An optical component comprising:
- a light guide adapted to conduct light under conditions of total internal reflection;
- a deformable layer adapted to conduct light under conditions of total internal reflection, the deformable layer having an upper surface disposed on a first surface of the light guide, the entire upper surface parallel to a second surface of the light guide; and
- an active layer, disposed on the deformable layer, that selectively reflects light by deforming a lower surface of the deformable layer to form a deformation such that the light within the deformable layer is reflected off the deformation and ejected from some portion of the second surface of the light guide.
2. (canceled)
3. The optical component of claim 1, wherein the deformable layer comprises an elastomer.
4. The optical component of claim 3, wherein the elastomer comprises silicone.
5. The optical component of claim 1, the active layer operable to be actuated by means of electrostatic attraction.
6. The optical component of claim 1, the active layer operable to be actuated by means of piezoelectric deformation.
7. An optical component comprising:
- a light guide adapted to conduct light under conditions of total internal reflection, at least a portion of the light guide being deformable; and
- an activc layer, disposed on the light guide, that selectively reflects light by deforming a first surface of the light guide such that the light is ejected from some portion of a second surface of the light guide, the active layer operable to be actuated by means of thermal expansion.
8. An optical component comprising:
- a light guide adapted to conduct light under conditions of total internal reflection, at least a portion of the light guide being deformable; and
- an active layer. disposed on the light guide, that selectively reflects light by deforming a first surface of the light guide such that the light is ejected from some portion of a second surface of the light guide, at least a portion of the active layer comprising an electro-active polymer.
9. The optical component of claim 1, at least a portion of the active layer comprising a piezoelectric film.
10. The optical component of claim 1, at least a portion of the active layer comprising a plurality of microelectromechanical systems.
11. The optical component of claim 1, at least a portion of the active layer comprising a plurality of nanoelectromechanical systems.
12. An optical component comprising:
- a light guide adapted to conduct light under conditions of total internal reflection, at least a portion of the light guide being deformable; and
- an active layer. disposed on the light guide, that selectively reflects light by deforming a first surface of the light guide such that the light is ejected from some portion of a second surface of the light guide, further comprising an anisotropic conductive film adhesive on at least a portion of the active layer.
13. The optical component of claim 1, at least a portion of the active layer coated with a plurality of small asperities.
14. The optical component of claim 13, the plurality of small asperities operable to cause multiple reflection points across substantially all of the deformation of the deformable layer.
15. An optical display comprising:
- a light source capable of outputting alternating pulses of light;
- a light guide coupled with the light source andadapted to conduct light under conditions of total internal reflection;
- a deformable layer adapted to conduct light under conditions of total internal reflection, the deformable layer having an upper surface disposed on a first surface of the light guide, the entire upper surface parallel to a second surface of the light guide;
- an active layer disposed on a deformable first surface of the light guide the deformable layer; and
- a driving layer coupled with the active layer and operable to selectively deform portions of the active layer that cause deformations in a lower surface of the deformable layer such that light within the deformable layer is reflected off the deformations and ejected from the second surface of the light guide in a controlled fashion.
16. The optical display of claim 15, the light source outputting visible light.
17. An optical display comprising: a driving layer coupled with the active layer and operable to selectively deform portions of the active layer such that light is ciected from a second surface of the light guide in a controlled fashion; a plurality of standoffs, each standoff situated between two of the plurality of deformable portions.
- a light source capable of outputting alternating pulses of light;
- a light guide coupled with the light source and adapted to conduct light under conditions of total internal reflection, each of a plurality of portions of the light guide being selectively deformable:
- an active layer disposed on a deformable first surface of the light guide;
18. The optical display of claim 17, at least one of the standoffs having a surface roughness of at least 100 nanometers.
19. An optical display comprising:
- a light source capable of outputting alternating pulses of light;
- a light guide coupled with the light source and adapted to conduct light under conditions of total internal reflection, at least a portion of the light guide, being deformable;
- a deformable layer adapted to conduct light under conditions of total internal reflection, the deformable layer having an upper surface disposed on a first surface of the light guide, the entire upper surface parallel to a second surface of the light guide;
- a plurality of modular active layers disposed in an arrayed manner on a deformable first surface of the light guide; and
- a plurality of modular driving layers, each driving layer module coupled with at least one of the modular active layers and operable to selectively deform at least a portion of the particular active layer to cause a deformation in a lower surface of the deformable layer such that light within the deformable layer is reflected off the deformation and ejected from the second surface of the light guide.
20. The optical display of claim 19, the light source outputting infrared light.
21. A method for fabricating an optical display comprising:
- selecting a light guide adapted to conduct light under conditions of total internal reflection;
- selecting a deformable layer adapted to conduct light under conditions of total internal reflection, the deformable layer having an upper surface disposed on a first surface of the light guide, the entire upper surface parallel to a second surface of the light guide;
- coupling a light source, capable of outputting alternating pulses of light, to the light guide; and
- arranging a plurality of modules on the deformable layer, each module comprising an active layer and a driving layer wherein the active layer is disposed on a lower surface of the deformable layer such that upon selective deformation of the active layer by the driving layer the active layer forms a deformation in a lower surface of the deformable layer that reflects the light and causes the light to eject from the second surface of the light guide.
22. The method of claim 21, wherein the light guide is manufactured by a first manufacturer and at least a portion of the modules are manufactured by a second manufacturer.
23. The method of claim 21, wherein the deformable layer comprises a deformable elastomer layer.
24. (canceled)
25. (canceled)
26. (canceled)
27. The method of claim 21, further comprising using a computer to cause the light source to output alternating pulses of light to the light guide.
28. The method of claim 21, further comprising using a computer to selectively apply a stimuli to the active layer to cause the selective deformation of the active layer.
29. The method of claim 28, the stimuli being selected from one of the following:
- electrostatic attraction;
- electromagnetic attraction;
- electromagnetic repulsion;
- piezoelectric. deformation;
- thermal expansion; and
- thermal contraction.
30. An optical component comprising:
- a light guide adapted to conduct light under conditions of total internal reflection;
- a deformable layer adapted to conduct light under conditions of total internal reflection, the deformable layer having an upper surface disposed on a first surface of the light guide, the entire upper surface parallel to a second surface of the light guide; and
- an active layer comprising a plurality of small asperities on the surface of the active layer. the active layer selectively reflects light by contacting the plurality of small asperities with a lower surface of the deformable layer thereby forming multiple reflection points in the lower surface of the deformable layer such that the light within the deformable layer is reflected off the multiple reflection points and ejected from some portion of the second surface of the light guide.
31. The optical component of claim 30, wherein the deformable layer comprises an elastomer.
32. The optical component of claim 31, wherein the elastomer comprises silicone.
33. The optical component of claim 30, wherein the small asperities comprise glass.
34. The optical component of claim 30, the active layer operable to be actuated by means of electrostatic attraction.
35. The optical component of claim 30, the active layer operable to be actuated by means of piezoelectric deformation.
36. The optical component of claim 30, at least a portion of the active layer comprising an electro-active polymer.
37. The optical component of claim 30, further comprising an anisotropic conductive film adhesive on at least a portion of the active layer.
Type: Application
Filed: Sep 21, 2006
Publication Date: Mar 27, 2008
Patent Grant number: 7751663
Inventor: Daniel K. Van Ostrand (The Woodlands, TX)
Application Number: 11/524,704
International Classification: G02B 6/10 (20060101);